I am not sure you want to use adhesive until you 110% understand how the normal handle install/remove is supposed to work. If you glued the thing together with some type of very secure adhesive without proper consideration you may never be able to remove the handle under conditions that the valve needs servicing.
– Michael Karas♦Mar 19 '17 at 19:47

Handle came preinstalled when bought this home. I looked around a little bit for guides; on Kohler website though thought to ask too; in case someone has dealt with this before; and could save me trouble of more searching. Any feedback is appreciated. Of course, I'll go search more if no answers; happy to post back when/if I do that.
– bmvakiliMar 19 '17 at 21:01

There appear to be female threads on the inside of the fitting. Perhaps it screws onto male threads not readily visible.
– Jim StewartMar 19 '17 at 23:03

Can you post another picture showing more details of the handle. Some questions come to mind. 1) Is the handle all one piece or is it two parts, one that normally is stationary and the other rotates? 2) In normal operation does the handle just rotate? 3) Does the handle have a up and down motion as well as turning?
– Michael Karas♦Mar 20 '17 at 0:09

Does the other side of the handle have a removable piece which would let you put a screw down the center of the shaft?
– brhansMar 20 '17 at 14:53

4 Answers
4

Saw this thread as I was having the same problem.The square socket is not stretched, it doesn't hold the handle in the wall (I thought the same thing at first). Here's the fix: pull off the large chrome/silver plate with the word KOLHER on it, it should pull off as it is not screwed into anything. It might have been caulked on the wall around the inside rim by the previous owner/installer to prevent water from getting in, but should pull off- just be careful not to pull out tiles. As someone else pointed out, the handle assembly actually should screw onto the black threaded part in the wall- it's just tricky and weird. It may be that the parts attached to the wall are too flush/recessed to the wall and the threads in the handle can't get onto the black plastic threaded part.

Now, with the chrome KOHLER plate removed from the wall, you will see two gold/brass screws, one on top and the other on the bottom. These screws hold the larger silver wall plate on the wall (the plate covers the hole in the wall). Loosen the gold/brass screws a bit, this will allow the plate against the wall be less recessed, and the black threaded part will also move out of the wall a bit. Put the metal KOHLER plate back on, and try to attach the handled by screwing it onto the black plastic part. The handle presses onto the KOHLER silver/chrome plate and holds in on the wall.

If it won't attach onto the black plastic, unscrew the gold/brass screws a bit more again to allow the black plastic part to be closer to the handle so that you can screw it on. I had to loosen the brass screws a few time because as I would get the handle on the black part and it screwed on, when I would tighten it firmly, the handle would pop off the threads because the black part was still too short. When pressing the handle onto the KOHLER silver/chrome plate, the KOHLER plate may spin. I actually got the handle screwed on a bit and started to just spin the KOHLER plate, which spun the handle and tightened it to the wall very nicely. This way, no glue/adhesive is needed.

Once you get it on, and understand how it works, you may want to take it all off and use caulk on the KOHLER ring to prevent water from getting in. This may protect water from getting in behind the wall.

It would slide onto the brass splines barely visible near the red bushing, and slide into the square recess on the handle.

It is used to allow the use of a non-standard handle. As such, there may be no way to lock it in place... As well the large diameter threads visible inside the handle would be part of the fitting it was cannibalized from.

Can you slide the adapter off the (assumed) splined shaft?

Edit: the Philips head screw inside the rectangular adapter (the one not on the handle) could be keeping the adapter on the splined shaft. But I can't see anyway to lock the adapter into the square recess in the handle; glue would allow one (1) assembly and zero (0) disassemblies. Sorry...

I suspect that the part that you linked would normally be used with the following part: amazon.com/Kohler-K73089-Short-Stem-Extension/product-reviews/… to extend out the shower faucet stem in cases where the bathroom wall was remodeled from an original installation through the addition of backer board and tile that made the wall thicker. Done correctly the original handle could have been used instead of the cannibalization that you suspect.
– Michael Karas♦Mar 20 '17 at 0:19

@DJohnM Just to make sure I understood you right: you're asking if I can take that piece off; that is, the Amazon part you linked to; whether I can slide it off of it's base. Well, I tried and I couldn't slide it off; however, I did not use any tools; would you recommend I use a plier? Or some sort of a wrench to twist the shaft? I think it would just spin the attached part; causing water to be turned on and such.
– bmvakiliMar 21 '17 at 3:22

@MichaelKaras and others, thanks for your help. AndrewMorton pointed out the square socket may be stretched and indeed that seems to be the issue.
– bmvakiliMar 22 '17 at 23:44

Glad to hear that the problem was that simple! It appears that there is a screw which fixes the square socket to the handle, so it should be easy to replace the socket. Make sure to sure use the correct screwdriver so that the head of the screw is not damaged. You'll want to replace it as soon as possible because once the socket is slightly damaged (stretched in this case), it will not be long before it breaks.
– Andrew MortonMar 24 '17 at 14:23